34CrMo4无缝钢管内折缺陷的成因分析  

Cause analysis of inner folding of 34CrMo4 seamless steel tube

作　　者：王潇 彭浩平[1,2,3] 雷云 苏旭平[2,3] 吴长军[2,3] 邓嵩[1] Wang Xiao;Peng Haoping;Lei Yun;Su Xuping;Wu Changjun;Deng Song(Jiangsu Key Laboratory of Oil and Gas Storage and Transportation Technology,Changzhou University,Changzhou Jiangsu 213164,China;Jiangsu Key Laboratory of Material Surface Science and Technology,Changzhou University,Changzhou Jiangsu 213164,China;Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering,Changzhou University,Changzhou Jiangsu 213164,China)

机构地区：[1]常州大学江苏省油气储运技术重点实验室,江苏常州213164 [2]常州大学江苏省材料表面科学与技术重点实验室,江苏常州213164 [3]常州大学江苏省光伏科学与工程协同创新中心,江苏常州213164

出　　处：《金属热处理》2020年第8期240-244,共5页Heat Treatment of Metals

基　　金：国家自然科学基金(51971039);江苏省高等学校自然科学研究项目(19KJA530001);江苏高校“青蓝工程”。

摘　　要：针对国内某型号34CrMo4无缝钢管生产过程中出现的钢管内折缺陷,利用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS),对缺陷微观形貌和微区成分进行了系统观察和分析,探讨了34CrMo4无缝钢管内折缺陷的形成原因。研究发现钢管内表面内折缺陷区域有大量层次明显的裂纹,并且在内折缺陷区域、生产线热加工后管坯和模拟生产线热处理后的管坯中均发现了Cu元素富集现象。在生产线管坯穿孔咬入过程中,高含Cu夹杂物被轧碎挤压至晶界处,并沿晶界渗入,破坏晶界的连续性。由于穿孔产生的轴向拉应力以及高含Cu夹杂物的出现,使管坯沿轴向变形过程中出现基体不连续现象,管坯在不断延伸过程中出现微裂纹,无缝钢管内壁在随后的连轧和定径过程中形成内折缺陷。Aiming at the inner folding defects of a domestic 34 CrMo4 seamless steel tube in the production process,optical microscope( OM),scanning electron microscope( SEM) and energy spectrometer( EDS) were used to carry out systematic inspection and analysis on microstructure and component of the defects.And the cause of formation of inner folding defects in 34 CrMo4 seamless steel tube were discussed.The results show that there are a large number of obvious cracks in the inner surface of the steel tube,and Cu enrichment is found in the inner folding area,when the tube blank after hot processing in the production line and the tube blank after heat treatment under simulated production line.During the perforation and biting process of the tube blank in the production line,high Cu-containing inclusions are crushed,squeezed to the grain boundary,and infiltrate along the grain boundary,finally,destroy the continuity of the grain boundary.Due to the axial tensile stress generated by the perforation and the presence of high Cu content inclusions,the matrix discontinuity is destroyed during the axial deformation of the tube blank.Therefore,micro-cracks appear during the continuous extension of the tube blank,and the inner folding defects are formed on the inner wall of the seamless steel tube during the continuous rolling and sizing process.

关 键 词：34CrMo4钢 无缝钢管 内折缺陷 元素富集 

分 类 号：TG178[金属学及工艺—金属表面处理]